The embodiments described herein relate generally to x-ray computed tomography and, more particularly, to computed tomography systems having compact geometry and highly uniform resolution throughout the field of view (“FOV”). Embodiments described herein also relate to processes for correcting artifacts in image data collected by a computed tomography system.
In at least some known computed tomography (“CT”) imaging systems, an x-ray source projects a fan-shaped or a cone-shaped beam towards an object to be imaged. The x-ray beam passes through the object, and, after being attenuated by the object, impinges upon an array of radiation detectors. Each radiation detector produces a separate electrical signal that is a measurement of the beam intensity at the detector location. During data acquisition, a gantry that includes the x-ray source and the radiation detectors rotates around the object.
Traditional designs for CT systems place the detectors on an arc that is centered on the focal spot. As a result, the ratio between the usable FOV and the outer diameter of the CT system is relatively small. A typical CT system capable of scanning an 85 centimeter opening is in excess of 200 centimeters in diameter. Additionally, CT systems of the prior art have a resolution that is highest at the center of the FOV and decreases toward the edges of the FOV.
Turning to the correction of artifacts in image data, it is known that ring artifacts due to detector errors affect CT systems. Methodologies for correcting those artifacts have been developed to correct slight non-linearities in the responses of neighboring, contiguous detector elements. However, such methodologies do not correct artifacts resulting from small, high density objects and edges as they transition through a differential scatter region in a CT system.